1. Field of the Invention
The disclosure relates to the production of acetic acid. More particularly, the disclosure relates to management of hydrogen iodide (“HI”) levels in acetic acid production.
2. Related Art
This section introduces information from the art that may be related to or provide context for some aspects of the technique described herein and/or claimed below. This information is background facilitating a better understanding of that which is disclosed herein. This is a discussion of “related” art. That such art is related in no way implies that it is also “prior” art. The related art may or may not be prior art. The discussion is to be read in this light, and not as admissions of prior art.
Production of acetic acid by methanol carbonylation is known. In the current acetic acid production process, a reaction mixture is withdrawn from a reactor and is separated in a flash tank into a liquid fraction and a vapor fraction comprising acetic acid generated during the carbonylation reaction. The liquid fraction may be recycled to the carbonylation reactor, and the vapor fraction is passed to a separations unit, which by way of example may be a light-ends distillation column. The light-ends distillation column separates a crude acetic acid product from other components. The crude acetic acid product is passed to a drying column to remove water and then is subjected to further separations to recover acetic acid.
Hydrogen iodide can be a reaction component in the production of acetic acid. Although process equipment generally used in the production of acetic acid is substantially inert to the reaction components, the equipment can still be corroded or otherwise adversely affected by HI. Additionally, HI can lead to the formation of long-chain alkyl iodide impurities, e.g., hexyl iodide, which are difficult to remove and which may complicate the recovery of acetic acid. Thus, the presence of HI can have consequences both in terms of corrosion of processing equipment and in terms of contamination of a final acetic acid product.
An improved acetic acid production process is thus needed which better manages levels of HI.